"Valid measurement is achieved when scores (including the results of qualitative classification) meaningfully capture the ideas contained in the corresponding concept." (Adcock and Collier 2001, 530)
Microwave popcorn;
Light salad dressings;
Flavored fat-Free Yogurt;
Dried Fruit;
Blue corn chips;
Cereal;
……
"Measurement is valid when the scores (level 4 in Figure 1), derived from a given indicator (level 3), can meaningfully be interpreted in terms of the systematized concept (level 2) that the indicator seeks to operationalize." (Adcock and Collier 2001, 531)
"Do you like pizza?"